This invention relates to electrode suspension bars, particularly, but not exclusively, to suspension bars for lead anodes and for copper cathodes used in electrolytic copper production, and for lead anodes used in electrolytic zinc production.
Conventionally, lead anodes for use in metal winning are cast around hard-drawn copper suspension bars which are supported at their extremities and contacted electrically by a current supplying busbar. Suspension bars made entirely of hard-drawn copper, and of sufficient cross-sectional area to carry the required electric current, are usually strong enough to carry the full weight of the anode. During the process, however, the copper becomes annealed, especially at the end of the suspension bar where the current is introduced. Bending of the bar during normal use may result, and more damage may be caused by mishandling when, for example, anodes are dropped or lowered too rapidly into a cell.
Similarly drawn copper bars, sometimes tubular, are used for suspending looped copper starter sheets in copper winning and refining and these are softened and bent in service in similar manner to the anode bars.
To provide extra strength, and for reasons of economy also, steel cored suspension bars are now being used. To avoid corrosion the steel core in such bars must be entirely enveloped by copper. Adequate current carrying capacity is ensured if the enveloping layer of copper is from 3 to 5 mm thick.
Occasionally, suspension bars made entirely of copper have notches at their ends to co-operate with a raised feature on the busbar. In this way location upon the busbar is facilitated, and electrical contact between the busbar and the suspension bar is improved. This practice has not hitherto been possible with steel cored suspension bars, however, because notching after enveloping with copper would expose some of the steel, and the application of a copper envelope to a steel bar already carrying a notch is not feasible.